Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$144.98	5.338%	$152.719	$152.72	$152.70	$152.70
Purchase #2	$10.40	10.750%	$11.518	$11.52	$11.50	$11.50
Purchase #3	$110.29	11.616%	$123.1013	$123.10	$123.10	$123.10
Purchase #4	$50.86	6.193%	$54.0098	$54.01	$54.00	$54.00
Purchase #5	$170.85	12.167%	$191.6373	$191.64	$191.65	$191.60
Purchase #6	$7.29	4.570%	$7.6232	$7.62	$7.60	$7.60
Purchase #7	$158.60	4.461%	$165.6751	$165.68	$165.70	$165.70
7 purchase totals =	$653.27		$706.2837	$706.29	$706.25	$706.20